Flea-Borne Typhus in Dogs

Flea-Borne Typhus is an infectious disease caused by the bacteriaRickettsia typhi(R. typhi). R. typhiis generally carried by rat fleas (although it can also be carried by cat fleas and mouse fleas). The infection causes Murine Typhus, which is also known as Endemic Typhus.

Occasionally, another rickettsial bacteria,R. felis, can also cause flea-borne typhus or clinically indistinguishable disease manifestations. There are other types of rickettsial diseases – Rocky Mountain Spotted Fever (RMSF) perhaps the most well-known – and several other forms of typhus, but Murine Typhus is the primary kind in which domesticated dogs and cats are thought to be a major part of the transmission cycle.

1. typhiandR. felis create natural reservoirs for disease by cycling between fleas in the environment and fleas on rodents, opossums, and free-roaming cats. Fleas that bite infected animals become infected and can further spread the disease to other animals or people.

Dogs are susceptible to infection, but primarily humans contract flea-borne typhus. The infection is acquired from infected flea dirt that contaminates open wounds or is inhaled. The flea bite itself can serve as an open wound for the bacteria to enter the body.

Overall, severe illness is rare in people. The disease is sometimes self-limiting, but serious manifestations and death can occur in rare circumstances, so you should promptly consult your doctor if you have any concerns regarding your health.

There is no vaccine that exists for the disease in humans or dogs, however, with proper diagnosis and care, flea-borne typhus can be treated with antibiotics and supportive care.

Fortunately, the disease is relatively uncommon in the United States – less than several hundred cases are reported in humans per year. However, the disease can be difficult to diagnose and may be underreported.

From the reports, flea-borne typhus in the U.S. is most common in (but not exclusive to) California, Texas, and Hawaii.R. felisandR. typhi bacteriaare commonly found in asymptomatic cats and opossums in these areas, although the prevalence in dogs is less well-studied.

In 2018-2019, several Southern California regions (Los Angeles County, Long Beach, and Pasadena) experienced a doubling in the documented human cases of flea-borne typhus. Improper waste disposal is thought to have attracted more rats, supporting a bigger population of infected fleas to spread the disease and creating a larger disease reservoir. This dramatic increase in cases emphasizes the importance of understanding, recognizing, and preventing further spread of flea-borne typhus.

Risk factors are related to flea exposure. For example, spending a lot of time outside and having close proximity to wildlife increases the chances of encountering infected fleas. Ultimately, keeping your dog protected from fleas and away from environments that harbor flea infestations will reduce the risk of your dog catching the disease or facilitating its transmission to humans.

In humans, flea-borne typhus can be associated with symptoms such as rash, fever, chills, headaches, muscle aches, and (in more rare instances) gastrointestinal or neurologic signs. In contrast, typhus-causing rickettsiae are not considered to cause clinical illness in dogs.

Although symptoms from Murine Typhus are not well documented in either dogs or cats, other rickettsial diseases carried by fleas and ticks (such as RMSF) can cause severe illness in pets. 

A veterinarian can detect a pet’s exposure to rickettsial diseases using a series of blood tests that identify antibodies or bacterial DNA. With regard to Murine Typhus, dogs may not have any noticeable symptoms throughout the course of infection or at the time of rickettsial antibody detection.

Since the clinical disease is uncommon, there is no standardized treatment protocol for dogs or cats. A veterinarian may consider antibiotics for flea-borne typhus (as is the treatment in humans) if the pet tests positive and has clinical signs that are suspected to be due to the disease.

The pillars of preventing flea-borne typhus are in good flea control measures. Flea control involves prevention for pets and for the environment.

For pets, it is recommended that dogs and cats have ongoing flea prevention – the best way to achieve this is to consult with your veterinarian on the most appropriate method for your pet, whether that is oral medications, topical medications, or other repellants.

Certain types of parasite preventative medications can be toxic to specific breeds of dogs or to cats, further highlighting the importance of consulting your veterinarian for the best choice.

Not only does flea prevention reduce the risk of your pet getting and spreading flea-borne typhus, but it also protects pets from multiple other diseases that fleas carry and the uncomfortable irritation or allergies that fleas cause pets.

Furthermore, many veterinary-prescribed flea preventatives also prevent ticks, mites, lice, and other external parasites (all of which have their own set of diseases and irritations!). If your pet isn’t already on one of these medications, it’s truly worth the visit to the vet to protect your pet.

Additionally, keeping your dog on-leash and out of heavily overgrown areas during walks and hikes helps prevent fleas, ticks, and other parasites from jumping onto your pet. Even if your pet is on a flea preventative, you should still check your pet’s fur regularly for signs of fleas, flea dirt, ticks, and other parasites. Contact your veterinarian if you have any concerns so that he or she can properly diagnose the issue and recommend the best treatment and prevention options.

Preventing fleas in the environment starts with your own home. Here are some of the actions you can take to reduce flea, rat, and wildlife populations (all drivers of flea-borne typhus) in your home and yard:

• Properly and promptly clean up any trash. Do not leave piles of trash or debris in your yard, garage, or home as these can attract rodents or wildlife as a place of shelter or source of food. Make sure trash bins have secure closures.
• Maintain a well-groomed yard. Keeping foliage and heavy vegetation pruned reduces both insect and rodent populations in the yard.
• Secure crawl spaces. Do this to prevent rodents and feral cats from making their own home under yours.
• Do not provide food or water for stray or wild animals. Doing this will attract all kinds of animals that can bring with them flea infestations.
• Feed your pet indoors & store your pet’s food indoors. Similarly, if you leave your pet’s food outdoors, it will attract other hungry animals.
• Maintain routine house cleaning. Keeping carpets, rugs, and pet beds clean helps prevent flea infestations from taking hold in the house.
• Address rodent and pest infestations. Call a professional if you may be dealing with an infestation.

Even if the prevalence of flea-borne typhus is relatively low in your area, these are good general recommendations to follow for your pet’s safety and your own health.

These same prevention measures can be helpful in controlling many other infectious flea-and-tick-borne diseases of pets and people – diseases such as plague, cat scratch fever, rabies, leptospirosis, and many others.

Flea-borne typhus is overall more of a public health concern than a direct threat to your dog’s health and wellbeing. Nonetheless, it is important to understand how you can do your part in preventing the disease to protect yourself, your pet, and those around you from infectious diseases that are harbored by fleas.

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